Inclusion Criteria (Affected Subjects):

• Male or female of any age;
• Suspected or confirmed diagnosis of leukodystrophy or other disorder affecting the white matter of the brain based primarily on the finding of central nervous system neuroimaging consistent with this diagnosis or on an existing diagnosis of a leukodystrophy or genetic leukoencephalopathy as defined in existing classification systems, or in the presence of variant(s) of uncertain significance or genotype consistent with leukodytrophy;
• Documentation of informed consent by the subject, parent, or legal guardian, and, if appropriate, documentation of assent;
• Willingness to provide clinical data, participate in standardized assessments, and/or provide biologic samples.

Exclusion Criteria (Affected Subjects)

• Established diagnosis at the time of referral that is not consistent with a genetic disorder of the white matter, such as an acquired demyelinating condition (e.g. multiple sclerosis), or an infectious etiology, with the exception of sequelae of congenital infections such as CMV;
• Inability to provide consent.

Inclusion Criteria (Healthy Controls)

• Male or female of any age;
• Individuals with no confirmed or suspected diagnosis of leukodystrophy or other disorder affecting the white matter of the brain (including affected patients' caregivers);
• Documentation of informed consent by the subject, parent, or legal guardian, and, if appropriate, documentation of assent.

Exclusion Criteria (Healthy Controls)

- Inability to provide consent.